Overview The TC426/TC427/TC428 are dual-channel CMOS high-speed drivers. A TTL/CMOS input level is translated into rail-to-rail output voltage swing. The CMOS output is at 25 mV of ground or positive supply. Low impedance, high current drive output swing 1000pF load at 30nsec18V. Unique current and voltage drive characteristics make the TC426/TC427/TC428 ideal for power MOSFET drivers, line drivers, and components of DC-to-DC converters. The input logic signal may be equal to the supply voltage. The input current is as low as 1mA, with the possibility of direct interface to CMOS/bipolar switching power control ICs, as well as to open-collector analog comparators. Quiescent supply current is 8mA max. The TC426 requires a 1/5 pin compatible bipolar current DS0026 device. This is important for DC-DC converter applications with efficiency constraints and power high frequency switching power supply applications. Quiescent current is typically 6mA driving a 1000pF load at 18V at 100kHz. The inverting TC426 drive pin is compatible with bipolar DS0026 and MMH0026 devices. The TC427 is non-inverting; the TC428 contains an inverting and non-inverting driver. Other pin-compatible driver families are TC1426/27/28, TC4426/27/28 and TC4426A/27A/28A.

Power supply bypasses charging and discharging large capacitive loads rapidly require large currents. For example, charging a 1000-pF load to18V in 25nsec requires a power supply from a 0.72A device. To ensure low source impedance over a wide frequency range, a combination of parallel capacitors is recommended for supply bypassing. Low inductance ceramic short lead length disk capacitors" (<0.5 inches) should be used. A one mF and its film capacitor in parallel with one or two 0.1uF ceramic capacitors usually provides sufficient disk bypassing.

ground
The inverting driver included in the TC426 and TC428. Ground potential drops in common ground impedance from input to output will appear as negative feedback characteristics that reduce switching speed. Input and output individual return ground circuits or ground planes should be used.

Input stage input voltage changes while no-load or quiescent supply current. The input stage transistor of the N-channel MOSFET drives a 2.5mA current source load. With a logic "1" input, the maximum quiescent current is 8 mA. A logic "0" input level signal reduces quiescent current by 0.4mA max. The lowest power consumption occurs with a logic "0" input for the TC426/427/428. Unused driver inputs must be tied to VDD or GND. The driver is designed with 100 mV of hysteresis. This provides clean transitions, reducing the current state of the output stage when spiking. The input voltage threshold is approximately 1.5V, making the device TTL compatible over a 4.5V to 18V supply operating range. Input current is less than 1 mA over this range. The TC426/427/428 can directly drive the TL494, SG1526/1527, SG1524, SE5560, and similar switch-mode power supply ICs.